The present invention relates to footwear, and more particularly to a sole construction for an article of footwear.
Running shoes, as well as other footwear, have undergone tremendous evolutionary advances in technology over the past 20 years. Many of the technological advances have occurred in the midsole and are the result of knowledge gained from biomechanical studies of human motion. In most footwear, the midsole functions as the suspension system of the sole and it often provides both protective cushioning and a stable platform for the wearer's foot. Many conventional technologies have focused on cushioning the impact associated with foot strike by varying the spring coefficients in the midsole to disperse shock. Relatively recent research has also provided significant clinical guidance in understanding how the complex motions of the foot affect human motion. As a result of that research, many conventional running shoes incorporate some type of stability device in the sole to help provide support to the intricate architecture of the foot. These biomechanical studies and related technological improvements have focused primarily on males, largely ignoring the biomechanical differences between men and women. Accordingly, most conventional biomechanically-designed footwear technology is tailored to address the biomechanical characteristics of a man.
As a result, studies show that women tend to suffer a disproportionate number of certain walking and running related injuries. For example, studies show that women have a higher incident of injury to the anterior cruciate ligament of the knee. It is believed by many that this is at least in part a result of the unique biomechanical characteristics of women. In many cases, these injuries are addressed by a podiatrist or an orthopedist, who may prepare custom orthotics that are designed to be fitted into the woman's shoes. These orthotics commonly address specific foot abnormalities by varying the shape of the foot using wedges, posts and other similar elements. The precise characteristics of the orthotic insert for a given person will vary based on the specific characteristics of that person's foot and the related injury. Although conventional wedges, posts and other similar elements may relieve pain and reduce the likelihood of repetitive injury for a person, they do so by reshaping the foot to address the specific abnormalities of that person's foot. Conventional orthotics do not properly address the issues raised by underlying differences in the body motion of women. In fact, podiatrists and orthopedists typically analyze the foot while it is not in a load bearing situation, crafting orthotics or other inserts based on the profile of unloaded feet as well as input from the patient. Further, conventional orthotic inserts are relatively expensive, requiring a person to engage an orthopedist or podiatrist. Additionally, orthotics and other conventional inserts are placed into the upper of a shoe. By occupying space intended for the foot, these inserts may have a negative impact on the fit and feel of the shoe. Orthotics are also unlikely to alleviate the problem of premature sole breakdown.